What to do to help my sister become less of a trouble maker?

You can't: Unless you are a professional therapist, you are not going to change your sister's behavior. This is a long term process consistently of a lot of introspection by the affected person and then hard work with behavioral therapy to create change. Thus, the person has to want to change. If she uses you as a sounding board, tell her you are not qualified to counsel her and to seek professional help.